// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
//

/**
 * Tiny Record RTC type.
 *
 * @module      tiny_recordrtc/base_recorder
 * @copyright   2022 Stevani Andolo <stevani@hotmail.com.au>
 * @license     http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

import {getString, getStrings} from 'core/str';
import {component} from './common';
import Pending from 'core/pending';
import {getData} from './options';
import uploadFile from 'editor_tiny/uploader';
import {add as addToast} from 'core/toast';
import * as ModalEvents from 'core/modal_events';
import * as Templates from 'core/templates';
import {saveCancelPromise} from 'core/notification';
import {prefetchStrings, prefetchTemplates} from 'core/prefetch';
import AlertModal from 'core/local/modal/alert';

/**
 * The RecordRTC base class for audio, video, and any other future types
 */
export default class {

    stopRequested = false;

    /**
     * Constructor for the RecordRTC class
     *
     * @param {TinyMCE} editor The Editor to which the content will be inserted
     * @param {Modal} modal The Moodle Modal that contains the interface used for recording
     */
    constructor(editor, modal) {
        this.ready = false;

        if (!this.checkAndWarnAboutBrowserCompatibility()) {
            return;
        }

        this.editor = editor;
        this.config = getData(editor).params;
        this.modal = modal;
        this.modalRoot = modal.getRoot()[0];
        this.startStopButton = this.modalRoot.querySelector('button[data-action="startstop"]');
        this.uploadButton = this.modalRoot.querySelector('button[data-action="upload"]');

        // Disable the record button untilt he stream is acquired.
        this.setRecordButtonState(false);

        this.player = this.configurePlayer();
        this.registerEventListeners();
        this.ready = true;

        this.captureUserMedia();
        this.prefetchContent();
    }

    /**
     * Check whether the browser is compatible.
     *
     * @returns {boolean}
     */
    isReady() {
        return this.ready;
    }

    // Disable eslint's valid-jsdoc rule as the following methods are abstract and mnust be overridden by the child class.

    /* eslint-disable valid-jsdoc, no-unused-vars */

    /**
     * Get the Player element for this type.
     *
     * @returns {HTMLElement} The player element, typically an audio or video tag.
     */
    configurePlayer() {
        throw new Error(`configurePlayer() must be implemented in ${this.constructor.name}`);
    }

    /**
     * Get the list of supported mimetypes for this recorder.
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/MediaRecorder/isTypeSupported}
     *
     * @returns {string[]} The list of supported mimetypes.
     */
    getSupportedTypes() {
        throw new Error(`getSupportedTypes() must be implemented in ${this.constructor.name}`);
    }

    /**
     * Get any recording options passed into the MediaRecorder.
     * Please note that the mimeType will be fetched from {@link getSupportedTypes()}.
     *
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/MediaRecorder/MediaRecorder#options}
     * @returns {Object}
     */
    getRecordingOptions() {
        throw new Error(`getRecordingOptions() must be implemented in ${this.constructor.name}`);
    }

    /**
     * Get a filename for the generated file.
     *
     * Typically this function will take a prefix and add a type-specific suffix such as the extension to it.
     *
     * @param {string} prefix The prefix for the filename generated by the recorder.
     * @returns {string}
     */
    getFileName(prefix) {
        throw new Error(`getFileName() must be implemented in ${this.constructor.name}`);
    }

    /**
     * Get a list of constraints as required by the getUserMedia() function.
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/MediaDevices/getUserMedia#constraints}
     *
     * @returns {Object}
     */
    getMediaConstraints() {
        throw new Error(`getMediaConstraints() must be implemented in ${this.constructor.name}`);
    }

    /**
     * Whether to start playing the recording as it is captured.
     * @returns {boolean} Whether to start playing the recording as it is captured.
     */
    playOnCapture() {
        return false;
    }

    /**
     * Get the time limit for this recording type.
     *
     * @returns {number} The time limit in seconds.
     */
    getTimeLimit() {
        throw new Error(`getTimeLimit() must be implemented in ${this.constructor.name}`);
    }

    /**
     * Get the name of the template used when embedding the URL in the editor content.
     *
     * @returns {string}
     */
    getEmbedTemplateName() {
        throw new Error(`getEmbedTemplateName() must be implemented in ${this.constructor.name}`);
    }

    /**
     * Fetch the Class of the Modal to be displayed.
     *
     * @returns {Modal}
     */
    static getModalClass() {
        throw new Error(`getModalClass() must be implemented in ${this.constructor.name}`);
    }

    /* eslint-enable valid-jsdoc, no-unused-vars */

    /**
     * Get the options for the MediaRecorder.
     *
     * @returns {object} The options for the MediaRecorder instance.
     */
    getParsedRecordingOptions() {
        const requestedTypes = this.getSupportedTypes();
        const possibleTypes = requestedTypes.reduce((result, type) => {
            result.push(type);
            // Safari seems to use codecs: instead of codecs=.
            // It is safe to add both, so we do, but we want them to remain in order.
            result.push(type.replace('=', ':'));
            return result;
        }, []);

        const compatTypes = possibleTypes.filter((type) => window.MediaRecorder.isTypeSupported(type));

        const options = this.getRecordingOptions();
        if (compatTypes.length !== 0) {
            options.mimeType = compatTypes[0];
        }
        window.console.info(
            `Selected codec ${options.mimeType} from ${compatTypes.length} options.`,
            compatTypes,
        );

        return options;
    }

    /**
     * Start capturing the User Media and handle success or failure of the capture.
     */
    async captureUserMedia() {
        try {
            const stream = await navigator.mediaDevices.getUserMedia(this.getMediaConstraints());
            this.handleCaptureSuccess(stream);
        } catch (error) {
            this.handleCaptureFailure(error);
        }
    }

    /**
     * Prefetch some of the content that will be used in the UI.
     *
     * Note: not all of the strings used are pre-fetched.
     * Some of the strings will be fetched because their template is used.
     */
    prefetchContent() {
        prefetchStrings(component, [
            'uploading',
            'recordagain_title',
            'recordagain_desc',
            'discard_title',
            'discard_desc',
            'confirm_yes',
            'recordinguploaded',
            'maxfilesizehit',
            'maxfilesizehit_title',
            'uploadfailed',
        ]);

        prefetchTemplates([
            this.getEmbedTemplateName(),
            'tiny_recordrtc/timeremaining',
        ]);
    }

    /**
     * Display an error message to the user.
     *
     * @param {Promise<string>} title The error title
     * @param {Promise<string>} content The error message
     * @returns {Promise<Modal>}
     */
    async displayAlert(title, content) {
        const pendingPromise = new Pending('core/confirm:alert');
        const modal = await AlertModal.create({
            title: title,
            body: content,
            removeOnClose: true,
        });

        modal.show();
        pendingPromise.resolve();

        return modal;
    }

    /**
     * Handle successful capture of the User Media.
     *
     * @param {MediaStream} stream The stream as captured by the User Media.
     */
    handleCaptureSuccess(stream) {
        // Set audio player source to microphone stream.
        this.player.srcObject = stream;

        if (this.playOnCapture()) {
            // Mute audio, distracting while recording.
            this.player.muted = true;

            this.player.play();
        }

        this.stream = stream;
        this.setupPlayerSource();
        this.setRecordButtonState(true);
    }

    /**
     * Setup the player to use the stream as a source.
     */
    setupPlayerSource() {
        if (!this.player.srcObject) {
            this.player.srcObject = this.stream;

            // Mute audio, distracting while recording.
            this.player.muted = true;

            this.player.play();
        }
    }

    /**
     * Enable the record button.
     *
     * @param {boolean|null} enabled Set the button state
     */
    setRecordButtonState(enabled) {
        this.startStopButton.disabled = !enabled;
    }

    /**
     * Configure button visibility for the record button.
     *
     * @param {boolean} visible Set the visibility of the button.
     */
    setRecordButtonVisibility(visible) {
        const container = this.getButtonContainer('start-stop');
        container.classList.toggle('hide', !visible);
    }

    /**
     * Enable the upload button.
     *
     * @param {boolean|null} enabled Set the button state
     */
    setUploadButtonState(enabled) {
        this.uploadButton.disabled = !enabled;
    }

    /**
     * Configure button visibility for the upload button.
     *
     * @param {boolean} visible Set the visibility of the button.
     */
    setUploadButtonVisibility(visible) {
        const container = this.getButtonContainer('upload');
        container.classList.toggle('hide', !visible);
    }
    /**
     * Handle failure to capture the User Media.
     *
     * @param {Error} error
     */
    handleCaptureFailure(error) {
        // Changes 'CertainError' -> 'gumcertain' to match language string names.
        var subject = `gum${error.name.replace('Error', '').toLowerCase()}`;
        this.displayAlert(
            getString(`${subject}_title`, component),
            getString(subject, component)
        );
    }

    /**
     * Close the modal and stop recording.
     */
    close() {
        // Closing the modal will destroy it and remove it from the DOM.
        // It will also stop the recording via the hidden Modal Event.
        this.modal.hide();
    }

    /**
     * Register event listeners for the modal.
     */
    registerEventListeners() {
        this.modalRoot.addEventListener('click', this.handleModalClick.bind(this));
        this.modal.getRoot().on(ModalEvents.outsideClick, this.outsideClickHandler.bind(this));
        this.modal.getRoot().on(ModalEvents.hidden, () => {
            this.cleanupStream();
            this.requestRecordingStop();
        });
    }

    /**
     * Prevent the Modal from closing when recording is on process.
     *
     * @param {MouseEvent} event The click event
     */
    async outsideClickHandler(event) {
        if (this.isRecording()) {
            // The user is recording.
            // Do not distract with a confirmation, just prevent closing.
            event.preventDefault();
        } else if (this.hasData()) {
            // If there is a blobsize then there is data that may be lost.
            // Ask the user to confirm they want to close the modal.
            // We prevent default here, and then close the modal if they confirm.
            event.preventDefault();

            try {
                await saveCancelPromise(
                    await getString("discard_title", component),
                    await getString("discard_desc", component),
                    await getString("confirm_yes", component),
                );
                this.modal.hide();
            } catch (error) {
                // Do nothing, the modal will not close.
            }
        }
    }

    /**
     * Handle a click within the Modal.
     *
     * @param {MouseEvent} event The click event
     */
    handleModalClick(event) {
        const button = event.target.closest('button');
        if (button && button.dataset.action) {
            const action = button.dataset.action;
            if (action === 'startstop') {
                this.handleRecordingStartStopRequested();
            }

            if (action === 'upload') {
                this.uploadRecording();
            }
        }
    }

    /**
     * Handle the click event for the recording start/stop button.
     */
    handleRecordingStartStopRequested() {
        if (this.mediaRecorder?.state === 'recording') {
            this.requestRecordingStop();
        } else {
            this.startRecording();
        }
    }

    /**
     * Handle the media stream after it has finished.
     */
    async onMediaStopped() {
        // Set source of audio player.
        this.blob = new Blob(this.data.chunks, {
            type: this.mediaRecorder.mimeType
        });
        this.player.srcObject = null;
        this.player.src = URL.createObjectURL(this.blob);

        // Change the label to "Record again".
        this.setRecordButtonTextFromString('recordagain');

        // Show audio player with controls enabled, and unmute.
        this.player.muted = false;
        this.player.controls = true;
        this.getButtonContainer('player')?.classList.toggle('hide', false);

        // Show upload button.
        this.setUploadButtonVisibility(true);
        this.setUploadButtonState(true);
    }

    /**
     * Upload the recording and insert it into the editor content.
     */
    async uploadRecording() {
        // Trigger error if no recording has been made.
        if (this.data.chunks.length === 0) {
            this.displayAlert('norecordingfound');
            return;
        }

        const fileName = this.getFileName((Math.random() * 1000).toString().replace('.', ''));

        // Upload recording to server.
        try {
            // Once uploading starts, do not allow any further changes to the recording.
            this.setRecordButtonVisibility(false);

            // Disable the upload button.
            this.setUploadButtonState(false);

            // Upload the recording.
            const fileURL = await uploadFile(this.editor, 'media', this.blob, fileName, (progress) => {
                this.setUploadButtonTextProgress(progress);
            });
            this.insertMedia(fileURL);
            this.close();
            addToast(await getString('recordinguploaded', component));
        } catch (error) {
            // Show a toast and unhide the button.
            this.setUploadButtonState(true);

            addToast(await getString('uploadfailed', component, {error}), {
                type: 'error',
            });

        }
    }

    /**
     * Helper to get the container that a button is in.
     *
     * @param {string} purpose The button purpose
     * @returns {HTMLElement}
     */
    getButtonContainer(purpose) {
        return this.modalRoot.querySelector(`[data-purpose="${purpose}-container"]`);
    }

    /**
     * Check whether the browser is compatible with capturing media.
     *
     * @returns {boolean}
     */
    static isBrowserCompatible() {
        return this.checkSecure() && this.hasUserMedia();
    }

    static async display(editor) {
        const ModalClass = this.getModalClass();
        const modal = await ModalClass.create({
            templateContext: {},
            large: true,
            removeOnClose: true,
        });

        // Set up the VideoRecorder.
        const recorder = new this(editor, modal);
        if (recorder.isReady()) {
            modal.show();
        }
        return modal;
    }

    /**
     * Check whether the browser is compatible with capturing media, and display a warning if not.
     *
     * @returns {boolean}
     */
    checkAndWarnAboutBrowserCompatibility() {
        if (!this.constructor.checkSecure()) {
            getStrings(['insecurealert_title', 'insecurealert'].map((key) => ({key, component})))
                .then(([title, message]) => addToast(message, {title, type: 'error'}))
                .catch();
            return false;
        }

        if (!this.constructor.hasUserMedia) {
            getStrings(['nowebrtc_title', 'nowebrtc'].map((key) => ({key, component})))
                .then(([title, message]) => addToast(message, {title, type: 'error'}))
                .catch();
            return false;
        }

        return true;
    }

    /**
     * Check whether the browser supports WebRTC.
     *
     * @returns {boolean}
     */
    static hasUserMedia() {
        return (navigator.mediaDevices && window.MediaRecorder);
    }

    /**
     * Check whether the hostname is either hosted over SSL, or from a valid localhost hostname.
     *
     * The UserMedia API can only be used in secure contexts as noted.
     * @see {@link https://developer.mozilla.org/en-US/docs/Web/API/MediaDevices/getUserMedia#privacy_and_security}
     *
     * @returns {boolean} Whether the plugin can be loaded.
     */
    static checkSecure() {
        // Note: We can now use window.isSecureContext.
        // https://developer.mozilla.org/en-US/docs/Web/Security/Secure_Contexts#feature_detection
        // https://developer.mozilla.org/en-US/docs/Web/API/isSecureContext
        return window.isSecureContext;
    }

    /**
     * Update the content of the stop recording button timer.
     */
    async setStopRecordingButton() {
        const {html, js} = await Templates.renderForPromise('tiny_recordrtc/timeremaining', this.getTimeRemaining());
        Templates.replaceNodeContents(this.startStopButton, html, js);
        this.buttonTimer = setInterval(this.updateRecordButtonTime.bind(this), 500);
    }

    /**
     * Update the time on the stop recording button.
     */
    updateRecordButtonTime() {
        const {remaining, minutes, seconds} = this.getTimeRemaining();
        if (remaining < 0) {
            this.requestRecordingStop();
        } else {
            this.startStopButton.querySelector('[data-type="minutes"]').textContent = minutes;
            this.startStopButton.querySelector('[data-type="seconds"]').textContent = seconds;
        }
    }

    /**
     * Set the text of the record button using a language string.
     *
     * @param {string} string The string identifier
     */
    async setRecordButtonTextFromString(string) {
        this.startStopButton.textContent = await getString(string, component);
    }

    /**
     * Set the upload button text progress.
     *
     * @param {number} progress The progress
     */
    async setUploadButtonTextProgress(progress) {
        this.uploadButton.textContent = await getString('uploading', component, {
            progress: Math.round(progress * 100) / 100,
        });
    }

    async resetUploadButtonText() {
        this.uploadButton.textContent = await getString('upload', component);
    }

    /**
     * Clear the timer for the stop recording button.
     */
    clearButtonTimer() {
        if (this.buttonTimer) {
            clearInterval(this.buttonTimer);
        }
        this.buttonTimer = null;
    }

    /**
     * Get the time remaining for the recording.
     *
     * @returns {Object} The minutes and seconds remaining.
     */
    getTimeRemaining() {
        // All times are in milliseconds
        const now = new Date().getTime();
        const remaining = Math.floor(this.getTimeLimit() - ((now - this.startTime) / 1000));

        const formatter = new Intl.NumberFormat(navigator.language, {minimumIntegerDigits: 2});
        const seconds = formatter.format(remaining % 60);
        const minutes = formatter.format(Math.floor((remaining - seconds) / 60));
        return {
            remaining,
            minutes,
            seconds,
        };
    }

    /**
     * Get the maximum file size that can be uploaded.
     *
     * @returns {number} The max byte size
     */
    getMaxUploadSize() {
        return this.config.maxrecsize;
    }

    /**
     * Stop the recording.
     * Please note that this should only stop the recording.
     * Anything related to processing the recording should be handled by the
     * mediaRecorder's stopped event handler which is processed after it has stopped.
     */
    requestRecordingStop() {
        if (this.mediaRecorder && this.mediaRecorder.state !== 'inactive') {
            this.stopRequested = true;
        } else {
            // There is no recording to stop, but the stream must still be cleaned up.
            this.cleanupStream();
        }
    }

    stopRecorder() {
        this.mediaRecorder.stop();

        // Unmute the player so that the audio is heard during playback.
        this.player.muted = false;
    }

    /**
     * Clean up the stream.
     *
     * This involves stopping any track which is still active.
     */
    cleanupStream() {
        if (this.stream) {
            this.stream.getTracks()
                .filter((track) => track.readyState !== 'ended')
                .forEach((track) => track.stop());
        }
    }

    /**
     * Handle the mediaRecorder `stop` event.
     */
    handleStopped() {
        // Handle the stream data.
        this.onMediaStopped();

        // Clear the button timer.
        this.clearButtonTimer();
    }

    /**
     * Handle the mediaRecorder `start` event.
     *
     * This event is called when the recording starts.
     */
    handleStarted() {
        this.startTime = new Date().getTime();
        this.setStopRecordingButton();
    }

    /**
     * Handle the mediaRecorder `dataavailable` event.
     *
     * @param {Event} event
     */
    handleDataAvailable(event) {
        if (this.isRecording()) {
            const newSize = this.data.blobSize + event.data.size;
            // Recording stops when either the maximum upload size is reached, or the time limit expires.
            // The time limit is checked in the `updateButtonTime` function.
            if (newSize >= this.getMaxUploadSize()) {
                this.stopRecorder();
                this.displayFileLimitHitMessage();
            } else {
                // Push recording slice to array.
                this.data.chunks.push(event.data);

                // Size of all recorded data so far.
                this.data.blobSize = newSize;

                if (this.stopRequested) {
                    this.stopRecorder();
                }
            }
        }
    }

    async displayFileLimitHitMessage() {
        addToast(await getString('maxfilesizehit', component), {
            title: await getString('maxfilesizehit_title', component),
            type: 'error',
        });
    }

    /**
     * Check whether the recording is in progress.
     *
     * @returns {boolean}
     */
    isRecording() {
        return this.mediaRecorder?.state === 'recording';
    }

    /**
     * Whether any data has been recorded.
     *
     * @returns {boolean}
     */
    hasData() {
        return !!this.data?.blobSize;
    }

    /**
     * Start the recording
     */
    async startRecording() {
        if (this.mediaRecorder) {
            // Stop the existing recorder if it exists.
            if (this.isRecording()) {
                this.mediaRecorder.stop();
            }

            if (this.hasData()) {
                const resetRecording = await this.recordAgainConfirmation();
                if (!resetRecording) {
                    // User cancelled at the confirmation to reset the data, so exit early.
                    return;
                }
                this.setUploadButtonVisibility(false);
            }

            this.mediaRecorder = null;
        }

        // The options for the recording codecs and bitrates.
        this.mediaRecorder = new MediaRecorder(this.stream, this.getParsedRecordingOptions());

        this.mediaRecorder.addEventListener('dataavailable', this.handleDataAvailable.bind(this));
        this.mediaRecorder.addEventListener('stop', this.handleStopped.bind(this));
        this.mediaRecorder.addEventListener('start', this.handleStarted.bind(this));

        this.data = {
            chunks: [],
            blobSize: 0
        };
        this.setupPlayerSource();
        this.stopRequested = false;

        // Capture in 50ms chunks.
        this.mediaRecorder.start(50);
    }

    /**
     * Confirm whether the user wants to reset the existing recoring.
     *
     * @returns {Promise<boolean>} Whether the user confirmed the reset.
     */
    async recordAgainConfirmation() {
        try {
            await saveCancelPromise(
                await getString("recordagain_title", component),
                await getString("recordagain_desc", component),
                await getString("confirm_yes", component)
            );
            return true;
        } catch {
            return false;
        }
    }

    /**
     * Insert the HTML to embed the recording into the editor content.
     *
     * @param {string} source The URL to view the media.
     */
    async insertMedia(source) {
        const {html} = await Templates.renderForPromise(
            this.getEmbedTemplateName(),
            this.getEmbedTemplateContext({
                source,
            })
        );
        this.editor.insertContent(html);
    }

    /**
     * Add or modify the template parameters for the specified type.
     *
     * @param {Object} templateContext The Tempalte context to use
     * @returns {Object} The finalised template context
     */
    getEmbedTemplateContext(templateContext) {
        return templateContext;
    }
}
